Timing is an extremely important Factor in the practice of forensic biology and pathology. This review offers an opportunity for evaluating the time at which an injury could have taken place and thus its chronologic-age.Both the macroscopic and microscopic aspects of the injury are discussed.The use of histochemical techniques using the study of enzymes as a basis of the technique is discussed. Histamine and serotonin techniques are also discussed and their applications in practical cases including a traffic accident are presented.The field is discussed and references given in large numbers.